The hydrocarbon lakes and seas of Saturn's moon Titan may erupt with dramatic patches of bubbles, NASA has revealed.

It says the phenomenon is similar to the bubbles when a soda bottle is opened.

Experts say the find could mean probes have to be redesigned to swim through 'fizzy' water.

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Cassini captured this mosaic of images showing the northern lakes and seas of Saturn's moon Titan on Feb. 17, 2017. The hydrocarbon lakes and seas of Saturn's moon Titan may erupt with dramatic patches of bubbles, NASA has since revealed.

Researchers at NASA's Jet Propulsion Laboratory in Pasadena, California, simulated the frigid surface conditions on Titan, finding that significant amounts of nitrogen can be dissolved in the extremely cold liquid methane that rains from the skies and collects in rivers, lakes and seas.

They demonstrated that slight changes in temperature, air pressure or composition can cause the nitrogen to rapidly separate out of solution, like the fizz that results when opening a bottle of carbonated soda.

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'Our experiments showed that when methane-rich liquids mix with ethane-rich ones - for example from a heavy rain, or when runoff from a methane river mixes into an ethane-rich lake - the nitrogen is less able to stay in solution,' said Michael Malaska of JPL, who led the study.

NASA's Cassini spacecraft has found that the composition of Titan's lakes and seas varies from place to place, with some reservoirs being richer in ethane than methane.

TITAN'S 'MAGIC ISLANDS'

The notion of nitrogen bubbles creating fizzy patches on Titan's lakes and seas is relevant to one of the more enchanting unsolved mysteries Cassini has investigated during its time exploring Titan: the so-called 'magic islands.'

During several flybys, Cassini's radar has revealed small areas on the seas that appeared and disappeared, and then (in at least one case) reappeared.

These images from the Radar instrument aboard NASA's Cassini spacecraft show the evolution of a transient feature in the large hydrocarbon sea named Ligeia Mare on Saturn's moon Titan. The images in the column at left show the same region of Ligeia Mare as seen by Cassini's radar during flybys in (from top to bottom) 2007, 2013, 2014 and 2015. The bottom image was acquired by Cassini on Jan. 11, 2015, and adds another snapshot in time as Cassini continues to monitor the ephemeral feature. The feature is apparent in the images from 2013 and 2014, but it is not present in other images of the region.

Analysis by Cassini scientists indicates that the bright features, informally known as the "magic island," are a phenomenon that changes over time.

They conclude that the brightening is due to either waves, solids at or beneath the surface or bubbles, with waves thought to be the most likely explanation.

They think tides, sea level and seafloor changes are unlikely to be responsible for the brightening.

Researchers proposed several potential explanations for what could be creating these seemingly island-like features, including the idea of fields of bubbles.

The new study provides details about the mechanism that could be forming such bubbles, if they are indeed the culprit.

The release of nitrogen, known as exsolution, can also occur when methane seas warm slightly during the changing seasons on Titan.

A fizzy liquid could also cause problems, potentially, for a future robotic probe sent to float on or swim through Titan's seas, the researchers say.

Excess heat emanating from a probe might cause bubbles to form around its structures - for example, propellers used for propulsion - making it difficult to steer or keep the probe stable.

'Thanks to this work on nitrogen's solubility, we're now confident that bubbles could indeed form in the seas, and in fact may be more abundant than we'd expected,' said Jason Hofgartner of JPL, who serves as a co-investigator on Cassini's radar team and was a co-author of the study.

In characterizing how nitrogen moves between Titan's liquid reservoirs and its atmosphere, the researchers also coaxed nitrogen out of a simulated ethane-rich solution as the ethane froze to the bottom of their tiny, simulated Titan lake.

Unlike water, which is less dense in its solid form than its liquid form, ethane ice would form on the bottom of Titan's frigid pools.

As the ethane crystalizes into ice, there's no room for the dissolved nitrogen gas, and it comes fizzing out.

While the thought of hydrocarbon lakes bubbling with nitrogen on an alien moon is dramatic, Malaska points out that the movement of nitrogen on Titan doesn't just move in one direction.

TITAN: EARTH'S 'TOXIC TWIN'

Aside from Earth, Titan is the only place in the solar system known to have rivers, rainfall and seas - and possibly even waterfalls.

Of course, in the case of Titan these are liquid methane rather than water on Earth.

Regular Earth-water, H2O, would be frozen solid on Titan where the surface temperature is -180°C (-292°F).

With its thick atmosphere and organic-rich chemistry, Titan resembles a frozen version of Earth several billion years ago, before life began pumping oxygen into our atmosphere.

Because Titan is smaller than Earth, its gravity does not hold onto its gaseous envelope as tightly, so the atmosphere extends 370 miles (595km) into space.

With Titan's low gravity and dense atmosphere, methane raindrops could grow twice as large as Earth's raindrops.

Clearly, it has to get into the methane and ethane before it can get out.

'In effect, it's as though the lakes of Titan breathe nitrogen,' Malaska said.

'As they cool, they can absorb more of the gas, 'inhaling.' And as they warm, the liquid's capacity is reduced, so they 'exhale.''

The new footage has been released by Nasa to mark the nearing end of the Cassini mission, as the spacecraft is due to descend in a self-destruct mission into fiery Saturn in September this year. The images reveal Titan's dunes are gigantic, reaching, on average, 0.6 to 1.2 miles (1 to 2 kilometers) wide, hundreds of miles (kilometers) long and around 300 feet (100 meters) high.

A similar phenomenon occurs on Earth with carbon dioxide absorption by our planet's oceans.

Recent footage released by Nasa shows exactly what it looks like to land on an alien world.

It may seem like stuff of science fiction, but the scenes in the new video happened in real life, 12 years ago.

The stunning video was captured when the space agency's Huygens probe descended onto the mysterious world of Titan, Saturn's biggest moon.

THE CASSINI MISSION

Since it left earth in 1997 and arrived at Saturn in 2004, Cassini has been touring the system with an up-close study of the planet, its rings and moons.

During its journey, Cassini has made dramatic discoveries, including a global ocean within Enceladus and liquid methane seas on Titan.

Before Nasa's Cassini probe captured the most detailed images of Saturn ever seen, it dropped its companion Huygens on the planet's largest moon, Titan.

After nearly 20 years in space, the mission is drawing near its end because the spacecraft is running low on fuel.

Before Nasa's Cassini probe captured the most detailed images of Saturn ever seen, it dropped its companion Huygens on the planet's largest moon, Titan - also known as Earth's toxic twin.

The video includes an animation showing this moment.

The new footage has been released by Nasa to mark the nearing end of the Cassini mission, as the spacecraft is due to descend in a self-destruct mission into fiery Saturn in September this year.

Huygens, a European Space Agency project, travelled to Titan as the companion to Nasa's Cassini spacecraft.

It then separated from its mothership on Christmas Eve, 2004, for a 20-day coast toward its destiny at Titan.

The new footage shows a series of images captured by a tiny camera on Huygens, pieced together into a video.

The video shows highlands of rugged ice as Huygens headed to the surface, with dried-up riverbeds seen from above.

'Twelve years ago, a small probe touched down on an orangish, alien world in the outer solar system, marking humankind's most distant landing to date, said Jim Green, director of planetary science at Nasa.

'Studying Titan helps us tease out the potential of habitability of this tiny world and better understand the chemistry of the early Earth.'

Images taken during the Huygens probe's descent revealed river channels and flood plains. The probe's cameras unveiled a plateau with a large number of dark channels cut into it, forming drainage networks that bore many similarities to those on Earth. The narrow channels converged into broad rivers, which drained into a broad, dark, lowland region. Earth-like river rocks, composed of water ice, were also observed at the Huygens probe landing site.

The video even reveals the parachute shadow from the Huygens lander, which is shown moving around. The location of the Huygens probe's resting place, a soft, sandy riverbed, was only confirmed after some time by the detection of two dark, longitudinal sand dunes, about 20 miles (30 kilometers) north of the landing site. The elusive landforms were visible in images from both Cassini radar and the probe. Radar evidence from Cassini suggests that flash flooding has sculpted streambeds on Titan with these rounded cobbles of water ice, which likely originated in water-ice bedrock in higher terrain.

Saturn's largest moon, Titan, is one of the solar system's most interesting places to study when it comes to the search for alien life.

The moon, with its lakes and clouds of liquid hydrocarbons, is the only place in the solar system other than Earth with an active weather cycle where rainfall erodes the landscape.

The stunning video was captured when the space agency's Huygens probe descended onto the mysterious world of Titan, Saturn's biggest moon 12 years ago. Pictured is an artist's impression of the probe

With its thick atmosphere and organic-rich chemistry, Titan resembles a frozen version of Earth several billion years ago, before life began pumping oxygen into our atmosphere.

But until Huygens landed on the moon, our understanding of just how interesting it is was limited.